The OR12D2 olfactory receptor gene, which codes for the G-protein coupled receptor (GPCR), carries the signal to sensory neurons to trigger smell and has 10 common variants and large effects on risk, was associated with autism in Arab-ancestry subjects and showed a high degree of linkage disequilibrium (p = 6.71 × 10−9) on the significant risk haplotype AAGTCTGATT. Here, OR12D2 is linked to autism.